Indigo is the only known source of blue textile dye, and while most natural dyes require boiling to extract the colour, indigo is extracted using a cold fermentation method which requires oxidisation. The cloth is dipped into the cold dye bath and emerges a greenish hue, which slowly turns to blue as the dye oxidises. Plants containing indigotin of different strengths can be found all over the world, but the plant illustrated here is Woad, which is native to Europe and produces a lighter cornflower blue.
Cochineal is a pink dye originating in Mexico, and is a parasitic insect which feeds off the native cacti. It was used in the region from as early as the 2nd century BC and is still used globally as a food and make-up colourant. The cultivation of cochineal is a low intervention crop which requires little water consumption and is a valuable harvest in arid regions where the climate is inhospitable to traditional crop cultivation. I use high quality cochineal bought directly from a family run company in Gran Canaria.
Yellow plant dyes are relatively easy to come by, and there are plenty of wild and cultivated plants in Scotland that can produce yellow hues. However, the biennial wildflower known as Weld produces the most light-fast and wash-fast yellow hues, and has been used as a dye since as early as the iron age. In the UK Weld was commonly used to dye over Woad blues to create a green hue since there are no dye plants that can create a strong green.
One of the most reliable sources of red dye comes from the root of the Madder plant, which is a herbaceous perennial. The earliest evidence of madder dye is from the 3rd millennium BCE in India, and it has been grown in the UK since the Viking era in the UK. The thick roots are harvested after 2-3 years growth and are an intense red colour which when boiled produce beautiful orangey red to pink hues.
Many common plants and foodstuffs can be used to dye cloth, however few natural dyes provide reliably light-fast and wash-fast colours. I use just a small palette of dyes, which have been known throughout history to produce strong lasting hues. These are madder, indigo, cochineal and weld.